Epic 1: Foundation - tooling, quality gates, test harness

Everything before the first page renders: a fresh SvelteKit app with strict tooling, the commit-time quality gate, Vitest and Playwright harnesses, and local Postgres with per-environment databases. Includes the one-off repo config: git config merge.ff false and pull.rebase false so ticket branches stay visible as no-ff bumps in history.

Done when a lint error, type error or failing unit test cannot be committed and e2e runs green against a dedicated test database.